Jude 1:3-4

3Beloved, while I was making every effort to write you about our common salvation, I was compelled to write to you [urgently] appealing that you fight strenuously for [the defense of] the faith which was once for all handed down to the saints [the faith that is the sum of Christian belief that was given verbally to believers].

4For certain people have crept in unnoticed [just as if they were sneaking in by a side door]. They are ungodly persons whose condemnation was predicted long ago, for they distort the grace of our God into decadence and immoral freedom [viewing it as an opportunity to do whatever they want], and deny and disown our only Master and Lord, Jesus Christ.